Automatic compression release mechanism

Abstract

An automatic compression release mechanism for implementation in an internal combustion engine, and a method of assembling such a mechanism, are disclosed. The mechanism includes a camshaft assembly including a cam gear, a cam lobe with a notch positioned along a first side of the gear, a tube passing through the gear and aligned with the notch, and a support on a second side of the gear. The mechanism additionally includes an arm including a weight and shaft coupled to one another, where an end of the shaft includes a recess, and where the shaft is rotatably positioned within the tube and the end of the shaft with the recess extends into the notch. The mechanism further includes a retaining member positioned onto the support so that the weight is positioned between the retaining member and the tube and retained with respect to the gear.

What is claimed is:  
     
       1. An automatic compression release mechanism for implementation in an internal combustion engine, the automatic compression release mechanism comprising: 
       a cam shaft assembly including  
       a cam gear,  
       a cam lobe positioned along a first side of the cam gear, the cam lobe including a notch;  
       a hollow tube passing from the first side of the cam gear to a second side of the cam gear and substantially aligned with the notch; and  
       a support extending from the second side of the cam gear proximate the hollow tube;  
       an arm including a weight and a shaft, wherein a first end of the shaft is fixedly coupled to a near end of the weight and a second end of the shaft includes a recessed portion, wherein the shaft is rotatably positioned within the hollow tube so that the weight is positioned along the second side of the cam gear and the second end of the shaft protrudes out of the hollow tube beyond the first side of the cam gear and into the notch; and  
       a retaining member positioned onto the support so that the weight is positioned in between the retaining member and the hollow tube and retained with respect to the cam gear.  
     
     
       2. The automatic compression release mechanism of  claim 1 , wherein the support includes a pillar, and the retaining member is a disk having a central orifice, the retaining member being positioned onto the pillar by positioning the pillar through the central orifice. 
     
     
       3. The automatic compression release mechanism of  claim 2 , wherein the weight is located in between a lip of the disk and the hollow tube. 
     
     
       4. The automatic compression release mechanism of  claim 3 , wherein the disk is at least one of metallic and plastic, and wherein the disk is a pushnut that has a central orifice that includes slots that project away from a central portion of the central orifice. 
     
     
       5. The automatic compression release mechanism of  claim 2 , wherein the support further includes a C-shaped ridge extending around the pillar, and wherein the pillar extends farther away from the second side of the cam gear than the C-shaped ridge. 
     
     
       6. The automatic compression release mechanism of  claim 5 , wherein the disk is positioned onto the support so that the pillar extends through the central orifice and so that the disk rests upon the C-shaped ridge. 
     
     
       7. The automatic compression release mechanism of  claim 6 , wherein the C-shaped ridge extends a sufficient distance away from the second side of the cam gear so that, when the disk rests upon the C-shaped ridge, the lip of the disk is at a proper position for retaining the weight against the hollow tube. 
     
     
       8. The automatic compression release mechanism of  claim 2 , wherein the pillar is made from plastic, and the retaining member is a flat washer. 
     
     
       9. The automatic compression release mechanism of  claim 8 , wherein the retaining member is fixed in its position with respect to the pillar by heating the pillar so that a portion of the pillar melts against the flat washer. 
     
     
       10. The automatic compression release mechanism of  claim 2 , wherein the retaining member is made from plastic and fixed in its position with respect to the pillar by at least one of heating and ultrasonically staking the retaining member with respect to the pillar. 
     
     
       11. The automatic compression release mechanism of  claim 2 , wherein the pillar is made from one of metal and plastic, and is threaded, and the retaining member includes a nut and a flat washer, where the flat washer is positioned to abut the weight and the nut is threaded onto the pillar to prevent the flat washer from moving off of the pillar. 
     
     
       12. The automatic compression release mechanism of  claim 1 , further comprising a spring coupled to the weight. 
     
     
       13. The automatic compression release mechanism of  claim 12 , wherein the cam shaft assembly further includes a central shaft that protrudes out of the second side of the cam gear, wherein the weight is biased by the spring toward the central shaft. 
     
     
       14. The automatic compression release mechanism of  claim 13 , wherein the arm rotates about the shaft increasingly far away from the central shaft as the cam shaft assembly rotates at increasingly high speeds. 
     
     
       15. The automatic compression release mechanism of  claim 14 , wherein at low speeds of the cam shaft assembly the arm is rotated so that a portion of the second end of the shaft protrudes out of the notch forming a bump along an exterior surface of the cam lobe, and wherein at high speeds of the cam shaft assembly the arm is rotated so that the recessed portion of the second end of the shaft no longer protrudes out of the notch. 
     
     
       16. The automatic compression release mechanism of  claim 15 , wherein at high speeds of the cam shaft assembly the weight is limited from rotating farther outward away from the cam shaft tube by at least one of an outer rim of the cam gear and an edge of a C-shaped ridge included as part of the support, and wherein the weight is arc-shaped. 
     
     
       17. An automatic compression release mechanism comprising: 
       a cam lobe;  
       a cam gear having a first side and a second side, the cam lobe abutting the first side;  
       an arm including a weighted portion positioned proximate the second side of the cam gear and a shaft fixedly coupled to the weighted portion and extending through a tube from the second side of the cam gear to and beyond the first side of the cam gear and into a notch within the cam lobe; and  
       means for retaining the arm in a substantially constant position with respect to an axis of the tube.  
     
     
       18. A method of assembling an automatic compression release mechanism on an internal combustion engine, the method comprising: 
       providing a camshaft assembly including a cam lobe and a cam gear having a first side and a second side, wherein the first side of the cam gear is adjacent to the cam lobe, wherein the cam lobe includes a notch along its exterior surface, wherein the cam gear includes a hollow tube that extends through the cam gear and is aligned with the notch along the first side of the cam gear, and wherein the cam gear further includes a pillar protruding from the second side;  
       providing an arm having a weight with a first side and a second side and a shaft having a first end and a second end, wherein the first end of the shaft is attached to the weight, and wherein the second end of the shaft includes a recessed portion;  
       inserting the shaft of the arm through the hollow tube so that the second end of the shaft including the recessed portion is positioned at least partly within the notch, and so that the first side of the weight is proximate the hollow tube; and  
       coupling a retaining member to the pillar so that at least a portion of the retaining member extends over the second side of the weight and prevents excessive movement of the shaft out of the hollow tube and excessive movement of the weight away from the second side of the cam gear.  
     
     
       19. The method of  claim 18 , wherein the cam gear further includes a C-shaped ridge extending from the second side of the cam gear and surrounding the pillar, wherein the C-shaped ridge extends less far from the second side of the cam gear than the pillar, wherein the retaining member is a disk with a central orifice, and wherein the retaining member is coupled to the pillar by slipping the central orifice over the pillar and pushing the retaining member down onto the pillar until the disk abuts the C-shaped ridge. 
     
     
       20. The method of  claim 18 , wherein the coupling of the retaining member includes at least one of: 
       positioning the retaining member onto the pillar and applying heat to the pillar and the retaining member, wherein the pillar is made from a plastic and the retaining member is metallic;  
       positioning the retaining member onto the pillar and applying ultrasonic vibration to the pillar and the retaining member; and  
       positioning a washer onto the pillar and screwing a nut onto the pillar over the washer to retain the washer, the washer and nut together forming the retaining member.